Code tables can be used to group other code tables in a hierarchy. Any number of code tables can be included in a code table hierarchy. A code table hierarchy allows the values available for selection in the drop-down field for one code table to be determined by the value selected in the drop-down field for another code table. For example, the values available when selecting the type of special caution to be recorded for a participant can be derived from the category of special caution selected. Code table hierarchies can be viewed and modified from the system administration application. For more information on code table hierarchies, please consult the Server Developers Guide.